I've got a Doug Thorley header with 2.5" piping (crush bent) to a magnaflow... It's a little on the loud side, but it helped power quite a bit._________________
The reason my car is older than me:
Toyota in 1983: "Why own a car when you can own the road?"
Toyota in 2005: "Oh, look...it carries groceries too!!"

2.25" pipe will keep things much quieter. A straight-thru muffler would create a nice tone w/out too much volume. 2.5" pipe pushes you into the "obnoxious" category pretty quickly depending on the muffler chosen. I finally settled on a LONG DynoMax SuperTurbo "hemi series" model. It's quite civil until I really step into it.

2.5" pipe will also cost you a slight bit of low-end response. 2.25" pipe will flow plenty for most modded 2xR engines.

Finding a Thorley header is tough. Some have gotten results contacting Thorley Headers directly, others have found NOS (new old-stock) headers at various distributors. The stock early manifold/downpipes are an awfully good factory setup, the aftermarket header is better. The later factory downpipe is a restrictive mess._________________'83 Celica GT-S coupe, EFI hybrid
Camas, WA USA
http://www.celica-gts.com/users/oldmagehttp://photobucket.com/albums/v368/OldMage/